1. Technical Field
The present invention relates to an optical diaphragm, a projector, a correction parameter calibrator, and a correction parameter calibrating method.
2. Related Art
Up to now, a projector has been known, which includes a light source device, an optical modulator for modulating a light beam irradiated from the light source device in accordance with image information to form an optical image, and a projection optical device for enlarging and projecting the optical image.
In order to adjust the amount of a light beam irradiated from the light source device to be incident upon the optical modulator for the purpose of enhancing contrast of a projected image or the like in such a projector, a projector having an opening/closing light shielding member (optical diaphragm) for partially shielding the light beam irradiated from the light source device has been proposed (see JP 2004-264819 A, for example).
The optical diaphragm described in the document has a pair of light shielding plates (light shielding vanes) each having a rectangular plate shape configured so as to rotate. Then, the optical diaphragm moves the light shielding vanes to desired positions with good precision by a driving device such as a pulse motor, thereby shielding against a light beam irradiated from the light source device in stages.
However, the optical diaphragm described in the above-mentioned document uses the pulse motor or the like as the driving device, so the size of the driving device inhibits the miniaturization of the optical diaphragm. Further, due to the vibration during driving of the driving device, stable driving cannot be realized.
Therefore, there is a demand for a technique capable of simplifying the configuration of an optical diaphragm, and moving light shielding vanes with high precision to perform stable driving.